#!/bin/sh# Calculation of the excitation energies of the open shell molecule CN# In this example, the lowest 20 excitation energies of CN are calculated in a# spin-unrestricted TDDFT calculation. In the MO -> MO transitions part for the# excitations of the output file, the spin of each molecular orbitals are also# specified to help assign the spin state of the excited states. The transitions# are always from alpha spin-orbital to alpha spin-orbital or from beta spin-# orbital to beta spin-orbital.$ADFBIN/adf <<eorTitle excitation energies of CNAtoms C .0000 .0000 .0000 N .0000 .0000 1.1718Endunrestrictedcharge 0 1excitations lowest 20 nto sfoanalysisendBasis Type AUG/ADZPEndeor
rm TAPE21 logfile
# Next the same example for CN is given with the Tamm-Dancoff approximation# (TDA) approximation (including TDA in the input). Due to this approximation# the calculated excitation energies will not be exactly the same as in the# first example.$ADFBIN/adf <<eorTitle excitation energies (TDA) of CNAtoms C .0000 .0000 .0000 N .0000 .0000 1.1718Endunrestrictedcharge 0 1excitations lowest 20 nto sfoanalysisendTDABasis Type AUG/ADZPEndeor
rm TAPE21 logfile
# Note that the basis set is still far from complete, the ATZ2P is better. For# accuracy reasons one may need to increase the numerical quality. If one uses# the augmented basis sets for accuracy reasons one could use NumericalQuality# Good.# The third calculation is the calculation of spin-flip excitation energies for# CN. Again these energies will not be exactly the same as in the first example.# For open-shell molecules, spin-flip transition can result in transition to the# ground state with a different S_z value, while the symmetry of the transition# density is A1 (Sigma+ for linear molecules). The excitation energy of this# transition should be zero and this can be used to test the reliability of# spin-flip TDDFT. Indeed the calculation of the spin-flip excitation energies# of CN shows one value which is close to zero and has a transition density of# Sigma+ symmetry.$ADFBIN/adf <<eorTitle spin-flip excitation energies (TDA) of CNAtoms C .0000 .0000 .0000 N .0000 .0000 1.1718Endunrestrictedcharge 0 1excitations lowest 20 nto sfoanalysisendSFTDDFTTDABasis Type AUG/ADZPEndeor
mv TAPE21 CN.t21
rm logfile